I've had ideas occasionally about building a fin jig. I have 5 builds starting so a good fin jig would be really helpful, but can I design and build a good one?
I've thought about it quite a bit. I was thinking about clamps, ways for things to slide, how to fit different tube sizes, and this was seeming to be pretty complicated. As I started working out the parts and how to build it I had ideas for how to make it simpler and eventually got it down to just a few pieces of wood. In the first picture you can see all of the parts, made from bits of scrap wood I had around.
In the last photo you can see how it works. I use rubber bands to hold the tube in the V blocks. I realized I could use gravity and not need any clamps, the fin just lays on the shelf and you slide it against the body tube. The glue is sticky enough to hold it in place. The shelf requires intricate adjustment to get the alignment right. I use cardboard and tape shims to adjust height of the shelf.
It's not quite perfect yet, I just put 4 fins on a Goblin. They don't align as well as I might be able to do by eye but the jig should be more consistent. After this first build I'll make another adjustment and see where it's at. For rockets with 3 fins it won't be as critical, with 4 fins the fins on opposite sides of the tube must align perfectly or you can easily see it.
The pieces of wood that have the V cut in them are about 2 1/8" wide, that's what the scraps of wood were, and this will fit up to a BT-80.
I've thought about it quite a bit. I was thinking about clamps, ways for things to slide, how to fit different tube sizes, and this was seeming to be pretty complicated. As I started working out the parts and how to build it I had ideas for how to make it simpler and eventually got it down to just a few pieces of wood. In the first picture you can see all of the parts, made from bits of scrap wood I had around.
In the last photo you can see how it works. I use rubber bands to hold the tube in the V blocks. I realized I could use gravity and not need any clamps, the fin just lays on the shelf and you slide it against the body tube. The glue is sticky enough to hold it in place. The shelf requires intricate adjustment to get the alignment right. I use cardboard and tape shims to adjust height of the shelf.
It's not quite perfect yet, I just put 4 fins on a Goblin. They don't align as well as I might be able to do by eye but the jig should be more consistent. After this first build I'll make another adjustment and see where it's at. For rockets with 3 fins it won't be as critical, with 4 fins the fins on opposite sides of the tube must align perfectly or you can easily see it.
The pieces of wood that have the V cut in them are about 2 1/8" wide, that's what the scraps of wood were, and this will fit up to a BT-80.